All pens have a valve action tip that only lets ink flow to the tip when you press the tip down. This allows the pens to dispense a wide variety of types of inks and solvents. Some pens have mixing balls.

Both pens have removable tips so you can easily replace the tip if it wears out without replacing the body.

The XNitePenXD has a machined metal screw cap that is removed for filling while the XNitePenHD is filled by pulling the valve action out of the pen body.